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    Subject[PATCH 12/12] lockdep: enable lock_page lockdep annotation
    With everything ready, connect the dots.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    ---
    include/linux/lockdep.h | 7 +++++++
    include/linux/pagemap.h | 10 ++++++++++
    mm/filemap.c | 35 +++++++++++++++++++++++++++++++++++
    3 files changed, 52 insertions(+)
    Index: linux-2.6/include/linux/lockdep.h
    ===================================================================
    --- linux-2.6.orig/include/linux/lockdep.h
    +++ linux-2.6/include/linux/lockdep.h
    @@ -253,6 +253,13 @@ extern void lockdep_init_map(struct lock
    struct lock_class_key *key, int subclass);

    /*
    + * To initialize a lockdep_map statically use this macro.
    + * Note that _name must not be NULL.
    + */
    +#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
    + { .name = (_name), .key = (void *)(_key), }
    +
    +/*
    * Reinitialize a lock key - for cases where there is special locking or
    * special initialization of locks so that the validator gets the scope
    * of dependencies wrong: they are either too broad (they need a class-split)
    Index: linux-2.6/include/linux/pagemap.h
    ===================================================================
    --- linux-2.6.orig/include/linux/pagemap.h
    +++ linux-2.6/include/linux/pagemap.h
    @@ -157,12 +157,22 @@ extern void FASTCALL(__lock_page(struct
    extern void FASTCALL(__lock_page_nosync(struct page *page, unsigned long ip));
    extern void FASTCALL(unlock_page_nocheck(struct page *page));

    +extern struct lockdep_map *page_lock_map(struct page *page);
    +
    static inline void __lock_page_check(struct page *page, int try, unsigned long ip)
    {
    + /*
    + * use recursive read locks to annotate the page lock.
    + * this allows us to have a single lock instance per filesystem.
    + * obviously this reduces the usefulness of the lock checker
    + * but it also keeps struct page from bloating.
    + */
    + lock_acquire(page_lock_map(page), 0, try, 2, 2, ip);
    }

    static inline void __unlock_page_check(struct page *page, unsigned long ip)
    {
    + lock_release(page_lock_map(page), 1, ip);
    }

    /*
    Index: linux-2.6/mm/filemap.c
    ===================================================================
    --- linux-2.6.orig/mm/filemap.c
    +++ linux-2.6/mm/filemap.c
    @@ -556,6 +556,41 @@ void end_page_writeback(struct page *pag
    }
    EXPORT_SYMBOL(end_page_writeback);

    +#ifdef CONFIG_DEBUG_LOCK_ALLOC
    +static struct lock_class_key lock_page_key;
    +static struct lockdep_map lock_page_map =
    + STATIC_LOCKDEP_MAP_INIT("lock_page", &lock_page_key);
    +
    +struct lockdep_map *page_lock_map(struct page *page)
    +{
    + struct address_space *mapping;
    + struct inode *inode;
    + struct super_block *sb;
    + struct file_system_type *type;
    + struct lockdep_map *map = &lock_page_map;
    +
    + mapping = page_mapping(page);
    + if (!mapping)
    + goto out;
    +
    + inode = mapping->host;
    + if (!inode)
    + goto out;
    +
    + sb = inode->i_sb;
    + if (!sb)
    + goto out;
    +
    + type = sb->s_type;
    + if (type)
    + map = &type->s_mapping_map;
    +
    +out:
    + return map;
    +}
    +EXPORT_SYMBOL(page_lock_map);
    +#endif
    +
    /**
    * __lock_page - get a lock on the page, assuming we need to sleep to get it
    * @page: the page to lock
    --

    -
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